Processors, memory devices, imagers, and other types of microelectronic devices are often manufactured on semiconductor workpieces or other types of workpieces. In a typical application, several individual dies (e.g., devices) are fabricated on a single workpiece using sophisticated and expensive equipment and processes. Individual dies generally include an integrated circuit and a plurality of bond-pads coupled to the integrated circuit. The bond-pads provide external electrical contacts on the die through which supply voltage, signals, etc., are transmitted to and from the integrated circuit. The bond-pads are usually very small, and they are arranged in an array having a fine pitch between bond-pads. The dies can also be quite delicate. As a result, after fabrication, the dies are packaged to protect the dies and to connect the bond-pads to another array of larger terminals that is easier to connect to a printed circuit board. The package can then be electrically connected to other microelectronic devices or circuits in many types of consumer or industrial electronic products.
Electronic product manufacturers are under continuous pressure to reduce the size of their products. Accordingly, microelectronic die manufacturers seek to reduce the size of the packaged dies incorporated into the electronic products. One approach to reducing the size of packaged dies is to reduce the thickness of the dies. For example, the backside of a wafer is often ground to reduce the thickness of the dies formed on the wafer. After backgrinding, the wafer is attached to a die attach film tape and then cut to singulate the dies. The die attach film tape includes a base and an adhesive layer on the base. After singulation, the dies are removed from the base and placed on a carrier tape for temporary storage. When the dies are removed from the base, sections of the adhesive layer remain attached to corresponding dies to facilitate subsequent attachment of the dies to a substrate for packaging. Conventional carrier tapes include a base and an adhesive layer on the base. For purposes of brevity and clarity, in this section the adhesive layer of the die attach film tape that remains attached to the dies will be referred to as the die attach adhesive, and the adhesive layer of the carrier tape will be referred to as the carrier tape adhesive. The singulated dies are attached to the carrier tape with the die attach adhesive facing the carrier tape adhesive.
One drawback of conventional carrier tapes is that each die needs to be removed from the carrier tape after a relatively short time (e.g., two to three weeks) because the bond between the die attach adhesive and the carrier tape adhesive strengthens over time. If a die is stored on a carrier tape for too long, several problems may result. First, removing the die can cause delamination between the die and the die attach adhesive because the bond between the die attach adhesive and the carrier tape adhesive may be stronger than the bond between the die attach adhesive and the die. Second, an increased force is required to separate the die from the carrier tape, and the increased force can crack or otherwise damage the die. Third, sections of the carrier tape adhesive may remain attached to the die attach adhesive after the die is removed, which reduces adhesive strength of the die onto the substrate or leadframe. The may result in delamination of the die from the substrate or leadframe due to insufficient adhesion to the latter. Accordingly, there is a need to improve the processing of semiconductor workpieces.